Epoxy-coated neodymium magnets are used when an NdFeB magnet needs added protection against moisture, humidity and corrosive exposure. The coating does not change the magnet grade itself; it acts as a protective barrier around the neodymium-iron-boron material.
Radial Magnets stocks multiple epoxy-coated neodymium magnets in disk, block, ring and mounting configurations, and can also source custom epoxy-coated parts for OEM and production programs.
Why Neodymium Magnets Need a Protective Coating
Neodymium-iron-boron (NdFeB) provides very high magnetic energy density, but the material is susceptible to oxidation and corrosion if the underlying magnet is exposed to moisture. For that reason, most finished neodymium magnets are plated or coated.
Standard nickel-copper-nickel (Ni-Cu-Ni) is common for general-purpose applications. Epoxy is often selected when the design calls for additional environmental protection, especially in humid, outdoor or moisture-prone service.
What Does an Epoxy Coating Do?
- Adds a corrosion-resistant barrier: Epoxy helps isolate the NdFeB substrate from moisture and other environmental exposure.
- Provides a nonmetallic outer finish: Many epoxy-coated magnets have a black finish that can also help visually distinguish them from nickel-plated parts.
- Supports outdoor and humid applications: Epoxy is commonly considered when standard nickel plating alone is not the preferred environmental solution.
Important: epoxy coating should not automatically be treated as “waterproof.” If the coating is scratched, chipped or damaged, the underlying magnet can become exposed. Applications involving continuous immersion, salt spray, chemicals, sterilization or aggressive cleaning should be qualified using the exact coating system and test requirements.
Epoxy vs. Nickel-Plated Neodymium Magnets
| Consideration | Epoxy Coating | Ni-Cu-Ni Plating |
|---|---|---|
| Corrosion protection | Often selected for added environmental protection | Good general-purpose protection |
| Typical appearance | Usually black | Silver / metallic |
| Scratch resistance | Can be damaged by abrasion or impact | Hard metallic surface, but still vulnerable if damaged |
| Magnetic grade | Does not change intrinsic NdFeB grade properties | Does not change intrinsic NdFeB grade properties |
| Best fit | Humidity, outdoor exposure, additional corrosion protection | General indoor and industrial use |
Any coating adds a small physical layer between the magnet and the mating surface. In tightly optimized magnetic circuits, coating thickness and the resulting working gap should be included in the design.
Common Applications for Epoxy-Coated Magnets
- Outdoor equipment and fixtures
- Sensors and position-detection assemblies
- Industrial automation
- Marine-adjacent or humid environments
- Mounting and holding systems
- Consumer products where a black finish is preferred
- OEM assemblies requiring an alternative to standard nickel plating
Epoxy-Coated Neodymium Magnets in Stock
Radial Magnets currently stocks several epoxy-coated neodymium magnet configurations, including:
| SKU | Configuration | Grade |
|---|---|---|
| 8007 | Disk, 1/4" × 0.1" | N42 |
| 8379 | Disk, 1/4" × 1/8" | N40 |
| 9770 | Disk, 6 mm × 2 mm | N35 |
| 9629 | Disk, 30 mm × 3 mm | N35 |
| 9417 | Block, 60 mm × 10 mm × 3 mm | N35 |
| 8314 | Ring, 0.375" OD × 3/16" ID × 1.5" | N42 |
| 9170 | Epoxy-coated pot magnet, 25 mm | N35 |
| 9472 | Epoxy-coated pot magnet, 32 mm | N35 |
Use Search Inventory to compare available sizes and grades. If the required size, grade, coating thickness or magnetization is not stocked, use the Magnet RFQ Builder for a custom or production quote.
How to Specify an Epoxy-Coated Magnet
For an OEM or production requirement, define more than just “epoxy coated.” A useful specification should include:
- Magnet material and grade
- Dimensions and tolerances
- Magnetization direction
- Epoxy coating system and color, if controlled
- Coating thickness or dimensional impact, when critical
- Operating temperature
- Humidity, immersion, salt-spray or chemical exposure requirements
- Required corrosion or adhesion testing
- Inspection, traceability and compliance documentation requirements
For production programs, Radial Magnets can also support quality and PPAP documentation and our Magnet Compliance Document Center.
Frequently Asked Questions
Are epoxy-coated neodymium magnets waterproof?
Not automatically. Epoxy improves environmental protection, but coating damage can expose the underlying NdFeB. Continuous immersion or chemically aggressive service should be validated to the exact application and coating specification.
Does epoxy coating make a magnet weaker?
It does not change the intrinsic magnetic grade of the NdFeB material. However, the coating adds a small physical gap, which can slightly affect measured force or field in very close-gap applications.
When should I choose epoxy instead of nickel?
Epoxy is often considered when additional corrosion protection, humid/outdoor exposure or a black nonmetallic finish is important. Nickel remains a common choice for general-purpose industrial use.
Can Radial Magnets supply custom epoxy-coated magnets?
Yes. Custom programs can specify geometry, grade, magnetization, coating system, tolerances, inspection and documentation requirements through the Magnet RFQ Builder or Bulk Magnet RFQ.
